A communication network may include network elements that route packets through the network. Some network elements may include a distributed architecture, wherein packet processing may be distributed among several subsystems of the network element (e.g., line cards, switches, etc.).
In many instances, communication networks may employ link aggregation. Link aggregation (e.g., IEEE 802.1AX-2008) may generally describe the practice of using multiple network cables or ports in parallel to increase the link speed beyond the limits of any one single cable or port. Link aggregation may also be used to provide fault protection by increasing redundancy for higher availability (e.g., by designating one or more “active” physical ports for carrying traffic and one or more “standby” physical ports for redundancy in the event of failure of an active port. In link aggregation, a group or set of ports may be combined and represented as a single logical port to other components of the network system. Various switching elements of the network system may “see” the aggregated ports (known as a “link aggregation group” or “LAG”) as a single logical communication port in the routing tables or databases of network elements external to the LAG.
Traditionally, control the various physical ports of a LAG and their statuses (e.g., active or standby) has been centralized, such that one line card of a plurality of line cards is designated as a “master”, maintaining status information and controlling ports for itself and the other line card, which may be designated as “slave” cards. However, such traditional approach has many disadvantages. For instance the centralized control plane may exist on a multiple line-card system and require powerful processing resources and a high-throughput communication channel to achieve real-time performance, which may lead to high hardware costs. Additionally, such centralized control may require complex synchronization among the various line cards, presenting challenges in developing and maintaining synchronization as well as high software costs. Further, in such centralized control, the master line card may be a single point of failure, and failure of the master line card may cause loss of link protection on an entire network element.